Telecommunications arrangements for businesses encourage productivity by enabling terminals to originate and terminate multiple calls simultaneously. For example, calls may be offered to a terminal when the user of the terminal is dialing a directory number or is active on another call. This eliminates the need for call waiting service and provides the user flexibility in choosing the call to handle next. In such an arrangement, each terminal has visual indicators, referred to as call appearances, for informing the user about the status of each call. Several, or even all, of the call appearances on a terminal may represent the same directory number. Furthermore, terminals may share call appearances. Calls alerting at a call appearance may be answered at any of the terminals that share the call appearance.
Shared call appearances are often used to provide call coverage. The terminal for a secretary who answers calls for several executives would include call appearances for the secretary's directory number and shared call appearances for the executives' directory numbers. If all the call appearances on the executives' terminals appeared on the secretary's terminal, the secretary could determine whether an executive's terminal was off-hook merely by glancing at the corresponding shared call appearances. However, since each executive's terminal is likely to have multiple call appearances, putting all the call appearances on the secretary's terminal is impractical. Instead, often only one call appearance of the executive's directory number appears on the secretary's terminal. The problem with this is that status information for the other call appearances is not available at the secretary's terminal so the secretary does not know whether the executive's terminal is off-hook. For example, assume a call from an important client arrives for an executive and the secretary answers the call. Meanwhile, the executive is off-hook and busy with a call on a call appearance that is not displayed on the secretary's terminal. The secretary, assuming that the executive is away from the desk, merely takes a message. Although the secretary quickly relays the message to the executive, the executive is unable to reach the client and loses an important business opportunity. In contrast, if the secretary's terminal had displayed information about the executive's other call appearances, the secretary would have recognized that the executive was on the phone and could be interrupted.
U.S. Pat. No. 4,873,717 issued to W. A. Davidson et al. on Oct. 10, 1989, discloses a call coverage arrangement in which coverage personnel are informed of the switch-hook status of covered terminals by way of a single two-part indicator on the covering terminal. The two-part indicator indicates switch-hook status for any one of a number of covered terminals. The first part of the indicator identifies the covered terminal and the second part defines the switch-hook status of the identified terminal. This arrangement does, however, require the use of shared call appearances to allow an incoming call to a covered terminal to ring and then be answered at a covering terminal. Shared call appearances are expensive to implement because of the required use of bridging circuits.
Telephone key systems have long been used to provide call coverage. Although key systems have the disadvantage of requiring additional adjunct equipment as well as many communication lines connected to each telephone, their operation from a human factors standpoint is considered to be highly desirable, particularly by experienced users.
In view of the foregoing, a need exists in the art for a call coverage arrangement which does not require large numbers of call appearances on a covering terminal or that call appearances be shared, bridged, or interconnected, but which allows calls to be answered promptly and efficiently and in a manner similar to the way calls are answered with key systems.